Spark-plug.



J. G. SHEA. smnx PLUG.

APPLICATION FILED JUNE 13,1908.

' Patented Mar. 23, 1909.

v Fig.1.

Fig. 2.

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INVENTOR s'wruesses- ATTORNEYS r JOHN G. SHEA, OF DETROIT, MICHIGAN.

SPARK-PLUG.

Specification of Letters Patent.

Patented March 23, 1909.

Application filed June 13, 1908. I Serial No. 438,265.

To all whom it may concern:

Be it known that I, JOHN G. SHEA, a citizen of the United States of America, residing at Detroit, in the county of- Wayne and State of Michigan, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification, reference being had therein to the accompanying drawings. I

This invention relates to spark plugs for internal combustion engines and consists in the matters hereinafter set forth, and more particularly pointed out in the appended claims. v

In the drawings, Figure 1 is a view in elevation of a spark lug embodying features of the invention. 1g. 2 is a view in longitudinal section at right an les to Fig. 1. Fig. 3 is a plan view of the lug. 2

Referring to the rawings, 1 indicates .a tubular nipple exteriorly taper screwthreaded for securin in the cylinder or combustion chamber wall of an explosive en inc in the usual manner. The upper cm is counterbored to receive a peripheral flange 2 of a bushing 3 of porcelain or like insulating material, a cap 4 screw-threaded on the nipple clamping the flan e against endwise movement between packing rings 5 of suitable material. A rod 6 of suitable material is secured in the bushing, its upper screwthreaded end enga ing a collar 7 on the up- )er end of the bushing, and having a hand ur 8 thereon which with the collar forms a convenient binding post or clamp. A transverse bar 9 or terminal secured in the lower end of the body is se arated from the projecting lower end 10 o the rod to form a suitable spark gap. The bushing below the flange is slightly tapered and is of less diameter than the bore of the nip le.

An open cup 11 is integra ly formed on or secured to the upper part of the nipple by an arm '12 and a duct 13 therefrom discharges into the annular s ace around the bushing just below the busliing collar. A manually operated rotatable valve plug 14 with a port 15 therethrough, controls the'cup duct, the plug being preferably disposed as shown with thumb piece 16 and retaining nut 17. One advantage of this arrangement is the fact that the valve forms a convenient means for blowing off the cylinder and this materially assists in cleansmg the terminals of the plug as the air blasts dislodge and sweep out any carbon in the terminals or the plug interior, while there is no need of ta ping an extra hole in the wall for a relief coc Another feature is the conducting of any priming charge placed in the cup downover the terminals, thereby burning oil any residue thereon when the charge is ignited and aiding in clearing the terminals that way while any extraneous matter lodged in, the annular space around the bushing is flushed or washed out.

The device is simple, and not readily thrown out of adjustment and obviates the necessity of tapping the cylinder or compression chamber wall for both plugs and reief and priming cocks.

Obviously changes in the details of construction may be made without departing from the spirit of the invention, and 1 do not care to limit myself to any particular form or arrangement of parts.

W'hat I claim as my invention is 1. A spark plug comprising a tubular nipple, an insulating bushing concentrically secured therein, a terminal in the bushing, a terminal in the nipple in operative relation to the bushing terminal, an arm on the upper end of the nipple, a priming cup on the arm discharging throu h a duct in the arm into the nipple above tlie terminals, and a manually operated shut off valve for the duct.

2. A spark plug comprising a tubular niple, an insulating bushing having a tapered ower end of less diameter than the; nipple. bore and a central flange secured in upper end of the nipple, an arm formed on the up per end of the nipple, a cup on the outer end of the arm connected by a passage through the arm to the nipple bore below the bushing collar, a terminal in the nipple below the bushing end, and a terminal extending through the bushing whose lower end is in operative relation to the nipple terminal.

3. A spark plu comprising a tubular, exteriorly screw hreaded nipple having a counterbored upper end, an axially apertured bushing having a central collar seated in the counterbored end of the bushin and a lower portion of less diameter than the nipple bore, a cap screw-threaded on the nipple clamping the collar in the nipple, a terminal rod extending through the bushing, a collar on the upper end of the bushing screw-v I Y 91e,sce

threaded on to the rod, a hand bur screwand a valve closure rotatabl secured at the threaded on the rod' above the collar, a terbase-of the cup controlling t e duct. 1? minal diametrically secured in the nipple be- In testimony whereof I afiix my signature low the bushing in operative relation to the in presence of two witnesses.

5 terminal rod, an arm extending from the u JOHN G. SHEA.

per end of the nipple, a priming cup on t e Witnesses: arm having a duct discharging through the O. R. STIOKNEY,

arm into the nipple below the bushing collar, WALTER A. GREENBU'RG. 

